TI中文支持网最近在看XINTF的文档，SPRU949d中External DMA Support节有如下阐述，
The XINTF supports direct memory access (DMA) to its local (off-chip) program and data spaces. This is accomplished with the XHOLD signal input and XHOLDA output. When XHOLD is asserted (low active) a request to the external interface is generated to hold all outputs from the external interface a high impedance state. Upon completion of all outstanding accesses to the external interface, XHOLDA is asserted (low active). XHOLDA signals external devices that the external interface has its outputs in high-impedance state and that another device can control access to external memory or peripherals
The HOLD Mode bit in XINTCNF2 register enables the automatic generation of a XHOLDA signal and granting access of the external bus, when a valid XHOLD signal is detected. While in HOLD mode, the CPU can continue to execute code from on-chip memory attached to the memory bus. If an attempt is made to access the external interface while XHOLDA is low, a not ready condition is generated, halting the processor. Status bits in the XINTCNF2 register will indicate the state of the XHOLD and XHOLDA signals.
觉得这两段话矛盾，XHOLD 将外部引脚全部变为高阻态，引脚全部状态不确定，二进制编码如何进行数据传输？
XHOLD A为低电平时，为何外部引脚全部变为高阻态，从XHOLD为低电平到XHOLD A为低电平，外部引脚一直为高阻态吧？
Hold模式，感觉是XHOLD A与XHOLD均为低电平时，数据开始在外部引脚传输。与第一段表达的XHOLD为低，开始数据传输，然后XHOLDA为低电平表明数据传输结束内容矛盾。
Hold模式下，cpu什么时候可以访问XINTF
